Re: Could I put commands in a variable

[James Edward Gray II]

On Feb 20, 2004, at 4:25 AM, Randy W. Sims wrote:

On 02/19/04 23:21, James Edward Gray II wrote:
On Feb 19, 2004, at 9:22 PM, R. Joseph Newton wrote:
I don't know, Rob.  I would be interested in hearing of any 
real-world problem that
would demand this.
I believe the text book example is a language that lacks support for 
something like Java's "finally" block.  A goto can guarantee you get 
to the code that must be executed, no matter the outcome of the 
current block.
James
One example of a legitimate use of goto from perlsub:

  Many "AUTOLOAD" routines load in a definition for the
  requested subroutine using eval(), then execute that sub-
  routine using a special form of goto() that erases the
  stack frame of the "AUTOLOAD" routine without a trace.
  (See the source to the standard module documented in
  AutoLoader, for example.)
The version of goto() your are talking about here, goto &NAME, is a 
little different from your standard goto().  From 'perldoc -f goto':

               The "goto-&NAME" form is quite different from the other 
forms
               of "goto".  In fact, it isn't a goto in the normal sense 
at
               all, and doesn't have the stigma associated with other 
gotos.
               Instead, it exits the current subroutine (losing any 
changes
               set by local()) and immediately calls in its place the 
named
               subroutine using the current value of @_.  This is used 
by
               "AUTOLOAD" subroutines that wish to load another 
subroutine and
               then pretend that the other subroutine had been called 
in the
               first place (except that any modifications to @_ in the 
current
               subroutine are propagated to the other subroutine.)  
After the
               "goto", not even "caller" will be able to tell that this 
rou-
               tine was called first.

               NAME needn't be the name of a subroutine; it can be a 
scalar
               variable containing a code reference, or a block which 
evalu-
               ates to a code reference.

James

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